524 



NATURE 



[October 27, 19 10 



all sides, and has frequently been referred to in our 

 columns. Owing to the continual growth of the 

 work, the director, who for many years has received 

 no financial help except from the observers themselves 

 and a few subscribers interested in the subject, has 

 in recent years had to meet a considerable deficit. 

 In order to ensure the undertaking " from the risks 

 of mortality," he has made over the unique collection 

 of documents and his interest in the concern to a 

 strong representative body of trustees, who have 

 formed an endowment fund, while Dr. Mill will con- 

 tinue to act as director, as before ; this arrangement 

 was referred to in our issue of June i6. 



Part i. includes an interesting article by Mr. Gethin 

 Jones on the snowfall of the Snowdonian range ; one 

 of the photographs shows a large patch of snow 

 lying on June 29 last; also a discussion of the duration 

 of rainfall in 1909 by the editor. In part ii., eighty 

 pages are occupied by observers' remarks; the director 

 has hinted elsewhere that the space might be more 

 serviceable for printing additional monthly values. In 

 addition to the usual tables, interesting chapters are 

 devoted to the discussion of heavy rains in short 

 periods and on rainfall days, with maps illustrating 

 some of the greatest falls. There are also maps 

 showing (i) the amount of rainfall and (2) percentage 

 of average, with a short discussion, for each month. 

 For the British Isles, as a whole, the rainfall of 

 the year (38'56 inches) was exactly the average ; but 

 during the last twenty-one years dry years have been 

 more than twice as frequent as wet ones. Reference 

 is made in the report to a crusade against entering the 

 rainfall to the wrong day. This is most important, 

 and, unless one rule is adhered to, accurate maps 

 of monthly rainfall cannot be drawn. But, notwith- 

 standing the efforts of meteorological conferences to 

 ensure uniformity, differences do still exist in some 

 of the best foreign services. To take only one case, 

 the Austrian "Instructions" (1905, p. 17) correctly 

 direct that, even when known to have fallen in the 

 early morning, the amount should be entered to the 

 previous day, while the Norwegian " Year Book " 

 (1909, p. ix) says the rainfall measured in the morn- 

 ing is entered to the preceding day, except when it is 

 known for certain that it fell after midnight. 



INDIAN CRUSTACEA. 



Catalogue of the Indian Decapod Crustacea in the 

 Collection of the Indian Museum. By Lt.-Col. 

 A. Alcock, F.R.S. Part i., Brachyura. Fasci- 

 culus i., Introduction and Dromides or Dromiacea 

 (Brachyura Primigenia). 1901. Pp ix + 80 + viii 

 plates. Price 7 rupees. Fasciculus ii., The Indian 

 Fresh-water Crabs — Potamonidae. 1910. Pp. iv + 

 135 + xiv plates. Price 14 rupees. (Calcutta.) 



"T^lIE 'Catalogue of the Indian Decapod Crustacea," 

 J- whicli is in course of publication by the Trustees 

 of the Indian Museum, Calcutta, consists of a series 

 of independent fascicles, each complete in itself, and 

 forming a systematic monograph of the Indian species 

 NO. 2139, VOL. 84] 



in the group with which it deals. The two parts 

 under notice relate to the Brachyura. The first, pub- 

 lished nine years ago, contains a general introduction 

 to the series giving an outline of the morphology of 

 the Decapoda, so far as it is necessary for systematic 

 purposes, and describing as a tvoe Nephrops anda- 

 manica, a form closely resembling the Norway lobster 

 of our own coasts. This is followed by a statement 

 of the characters distinguishing the Brachyura or 

 true crabs, and a sketch, all too short, of their bio- 

 nomics, with special reference to the Indian species, 

 prefacing a systematic account of those belonging to 

 the Tribe Dromiacea. This tribe is of special interest 

 on account of the very primitive character of some of 

 its members, which enable the origin of the Brachyura 

 to be traced bade, as Bouvier showed, to the lobster- 

 like Nephropsidea. Many important types were cap- 

 tured bv the Investigator in the Bay of Bengal, and 

 are fully described and figured in this fascicle. 



The group of Brachyura dealt with in the second 

 fascicle is also of special interest, although for very 

 different reasons. The river-crabs of the family Pota- 

 monidae (formerly known as Telphusidae) are found 

 in fresh waters throughout the tropical regions of the 

 world. Their geographical distribution has been 

 especially studied by Dr. A. E. Ortmann, who used it 

 in his ingenious speculations regarding the former 

 distribution of land and water on the surface of the 

 globe. The geographical relations of any group of 

 organisms, however, can only be studied with profit 

 when their systematic relations have been determined 

 with some degree of certainty, and it happens that 

 the river-crabs, like many other groups of fresh-water 

 animals, present special difliculties to the systematist. 

 There has hitherto been no general agreement with 

 regard to the limits, not only of species and varieties, 

 but even of genera and subfamilies, and the very 

 valuable monograph of the family recently published 

 by Miss M. J. Rathbun in the Archives of the Paris 

 Museum, while immensely lightening the task of 

 subsequent workers, made very obvious the unsatis- 

 factory character of much of our knowledge of the 

 group. Lt.-Col. Alcock now directs attention to cer- 

 tain structural characters, hitherto for the most part 

 overlooked, which enable the species to be grouped in 

 well-defined categories, and he proposes an entirely 

 new classification, in which species hitherto placed side 

 by side in the same subgenus are widely separated in 

 distinct subfamilies. The application of this classifi- 

 cation to the river-crabs inhabiting other regions is 

 only hinted at in this memoir, but there can be no 

 doubt that it will greatly modif)' our conceptions of 

 their geographical relations. 



In the power of terse and lucid description, in the 

 acute perception of systematic affinities, and in tlie 

 breadth of view derived from a familiarity with many 

 diverse groups of the animal kingdom, Lt.-Col. 

 .Mcock has few equals among living carcinologists, 

 and it is a matter for congratulation that his retire- 

 ment from the post of superintendent of the Indian 

 Museum has not terminated the long series of im- 

 portant memoirs on the Indian fauna which we owe 

 to his pen. W. T. C. 



